The present invention is directed to an improved container for transporting and storing hazardous chemicals which meets current regulations for interstate and international shipments, and prevents leakage and discoloration of chemicals.
Most hazardous chemicals are presently shipped in bulk, such as by railroad tank cars or tank trucks, or in all-steel drums which meet current U.S. Department of Transportation (hereinafter "DOT") and International Maritime Consultative Organization (hereinafter "IMCO") requirements. Such requirements have been interpreted to preclude the use of drums containing exposed plastic fittings or surfaces. Accordingly, the conventional open-head drums currently in use are fabricated almost entirely of steel, or some equivalent metal or alloy. However, since many chemicals commonly being transported in these drums will readily attack and corrode a steel surface, such drums are usually provided with an inner lining of a protective material, typically a phenolic resin, which is intended to be resistive to chemical attack. See, for example, U.S. Pat. No. 3,445,031 to Dubois et al, issued May 20, 1969, and U.S. Pat. No. 2,748,673 to Winstead, issued Mar. 9, 1951. Unfortunately, this type of protection is usually not adequate for the shipment and storage of many organic chemicals which readily attack or permeate conventional plastic linings and attack the steel inner surface of the drum. For example, some chlorinated organic chemicals, such as benzoyl chloride, hydrolyze upon contact with moisture in the drum to generate hydrochloric acid in situ. The hydrochloric acid readily attacks the inner lining of the drum, penetrating the lining to the inner steel surface. As a result, the hydrochloric acid degrades the lining and reacts with the steel surface causing discoloration of the benzoyl chloride. Such discoloration renders the benzoyl chloride unsuitable for use in many commercial applications. Furthermore, the interior surface of the drum can become sufficiently corroded so as to prevent reuse of the drum. In practice, therefore, the shelf life of conventional drums which are used to ship chemicals such as benzoyl chloride is frequently less than about three (3) months, after which time the quality of the benzoyl chloride will deteriorate substantially.
Various proposals have been advanced to develop improved containers for shipping benzoyl chloride. However, such proposals have not proven entirely successful. These proposals have, in general, involved two approaches: (1) modification of the interior of an existing steel drum which presently meets current DOT and IMCO standards, and (2) development of a new drum which will be exempt from DOT and IMCO regulations. As an example of the first approach, it has been suggested to use a low density polyethylene liner approximately 0.015 inches in thickness in a steel drum. However, it has been found that the benzoyl chloride in the drum will readily permeate the liner, causing discoloration of the bulk of the benzoyl chloride in a relatively short time. Steel drums with flexible plastic linings, such as disclosed in U.S. Pat. Nos. 2,748,673, supra, 3,918,605 to Butler, issued Nov. 11, 1975, and 2,912,136 to Redmond et al, issued Nov. 10, 1959, are similarly not suitable for transporting benzoyl chloride.
Plastic drums, such as disclosed in U.S. Pat. No. 4,094,432, to Zilbert, issued June 13, 1978, exemplify the second approach. However, the use of such drums in commerce requires a specific exemption from DOT requirements which is a time consuming procedure. In addition, although such plastic drums would be resistant to chemical attack by hydrochloric acid, they would also have a relatively low structural strength, even with a comparatively thick side wall section, which would prevent storage of such drums in heights of more than two tiers, even with the use of pallets.
U.S. Pat. No. 2,912,136, supra, discloses a drum with a metal cover and having a flexible bag-like liner with two (2) openings in the top wall portion fitted with liquid-tight rubber plugs. Since the liner is unsupported within the drum, rupture or failure of the liner represents a significant safety hazard to personnel involved in transporting and storing the drum and examining and removing its contents.
Accordingly, it is a principal object of the present invention to provide an improved drum for transporting hazardous chemicals which will meet current DOT and IMCO requirements, and can utilize existing materials and components of construction with minimal modification. It is a further object of this invention to provide a drum for transporting benzoyl chloride which will prevent its premature discoloration and leakage during shipment and storage.